Many veterinary pharmaceuticals and other veterinary formulations include components that taste very bitter or are otherwise distasteful or undesirable to one or more senses of an animal, so that the animal refuses to take the composition orally when offered. Anyone who has ever tried to give medicine to a pet dog or cat knows how difficult the process can be. Dogs and cats do not eat tablets willingly and are highly suspicious of liquids and powders. Their acute sense of smell will often warn them that their owner is approaching with some form of unpleasant medicine even when medicine is hidden in a treat.
Examples of such unpleasant medicines are anthelmintic veterinary formulations containing the active ingredient praziquantel. Praziquantel tastes very bitter and refused by virtually all dogs offered the active ingredient without some type of taste masking. Even with taste masking, in some instances, an animal may take the offered composition in its mouth, but then spit it out once it becomes aware of the bitter taste. Further, sometimes the animal will take the composition when it is first offered to it, but then learns that it has a bad taste, texture or other undesirable trait and will refuse the medicine on subsequent offerings.
Another drawback of praziquantel lies in the dosage size. A single dose of praziquantel may require a large single tablet or two or more regular-sized tablets. A large single tablet is not easily given to a pet, and, once taken, the pet will quickly learn to resist taking the second and subsequent tablets. An animal becomes more and more reluctant to take additional tablets with each subsequent tablet. With some highly unpleasant active ingredients and for a big animal, perhaps as many as ten taste-masked tablets could be required for a therapeutic amount of medicine masked by a sufficient amount of a masking agent to get the animal to take a therapeutic dose. The animal could easily lose interest in taking additional tablets, and an owner could also lose heart. Without proper dosing, the therapeutic purpose of the medicine could be reduced or lost entirely.
Various types of masking agents have been utilized in the past to hide or mask the taste of medicines so that an animal will take it. Sometimes, masking various ingredients by coating them with sufficient neutral or palatable material will encourage the animal to take the offered medicine. However, if the animal bites through the tablet given in this manner, the animal will often discover the undesirable taste and will refuse to consume it. One approach used in pharmaceuticals, microencapsulation, is too expensive for an animal health product.
Animals often perceive whether they like something or not first, and sometimes principally, by smell. The taste and/or texture and chewability or mouthfeel also come into play once the animal has the product in its mouth. With respect to texture and chewability, dogs normally like products that are chewy rather than hard and brittle. Consequently, a self-take veterinary medicine must appeal to the animal's senses of smell and taste, as well as texture and mouthfeel and any other relevant senses in order to entice the animal to take the product in its mouth and then consume it completely. Tablets are especially difficult to administer to dogs because they can be harder and more brittle than other delivery forms.
Taste and smell masking agents have been used to improve the animal's perception of a veterinary medicine by diluting unpleasant active ingredients in a substantial amount of a carrier. The carrier masks or conceals the smell or taste of the unpalatable medicinal component. Dilution of the unpalatable actives can become a problem when large amounts of an active ingredient must be administered to the animal. The large amount of active requires a proportionally large amount of a masking agent to fool an animal's senses. As noted before, some anthelmintic compounds, especially praziquantel, require a fairly large dose of active component to be therapeutically effective and cannot be easily masked with a small amount of a masking agent. To mask such a composition effectively requires a significant amount of masking agent, which, in turn, can make a tablet too large for the animal to take without chewing. This size problem becomes especially difficult when the masking agent is not highly effective in masking the bitter tasting active, thereby requiring an even larger amount of masking agent to be used in the formula.
Tableting machines in the pharmaceutical industry are also designed for conventionally sized tablets, and therefore typical tableting machines are limited in the volume of material that can be handled and produced for a specific tablet size. Such machines cannot handle the large amount of mixed active and masking agent that may be required for many taste-masked tablets. If a very strong compression force is required to force a large amount of material into a single regular size tablet, the tablet may then be too hard and brittle and therefore rejected by the target animal.
The art still needs a tablet and manufacturing process for a large dose veterinary medicine that can be effectively and economically masked by a relatively low amount of a taste or smell masking agent.